This invention relates to a reducing material for use in steel making, particularly in the making of stainless steel, to promote reduction of oxides of such metals as iron, chromium and the like and desulphurization of the molten steel, to thereby improve the steel quality and production efficiency.
In the reducing period of the refining process in stainless steel making, silicon is normally added as a reducing material to remove oxygen supplied in excess during the preceding oxidizing period and to reduce the oxidized alloying elements such as Cr, Mn and Fe. The addition of silicon, however, causes production of silicon oxide, which reduces basicity of the slag thereby impeding the desulphurization.
On the other hand, in order to carry out the reducing process effectively it is essential to add silicon in a certain excessive quantity and in order to maintain the basicity of the slag at a proper level a considerable quantity of lime and the like is needed. Addition of such a considerable quantity of lime and the like increases the quantity of slag, makes control of Si content in the molten steel difficult and thus interferes with the steel making operation.
Further, when metallic aluminum having a higher reducibility than silicon is added in an uncoated state, the metallic aluminum will violently react with oxygen in the air in the high temperature atmosphere and will be rapidly consumed contributing little to reduction of the oxides in the slag and desulphurization of the molten steel.